1. Field of the Invention
The present invention relates to a volume type phase hologram member with which a three-dimensional image can be viewed, for example, on a flat-sheet-like film, and more particularly to a hologram member with which a hologram can be simply and easily provided at a desired place by transfer.
2. Related Background Art
Holography is a technique by which an object is irradiated by a sufficiently coherent wave of light such as a laser beam where the wave is modulated in the amplitude and phase in accordance with the shape of the object, the modulated light reflected upon or transmitted through it is received on a photosensitive material and recorded, and a hologram thus formed is irradiated by light to reproduce an optical image of the object thereby recorded. Thus, a three-dimensional optical image can be viewed, for example, on a flat-sheet-like film.
With development of researches on such holography, at present time it has been made considerably clear what are required for the photosensitive materials (or recording materials). Known as the photosensitive materials usable in hologram formation are various materials including bleached silver salts, photoresists, thermoplastic resins, dichromate gelatin, inorganic glass materials, ferroelectric materials, etc., and researches are further being made on the suitability of the materials to the holography.
The properties which the photosensitive materials for use in forming a hologram should have can be enumerated, for example, as follows:
(1) a sensitivity to a laser beam, particularly to a laser beam of the visible wavelength region, and the sensitivity being high. PA0 (2) a high resolving power; PA0 (3) a high diffraction efficiency of hologram; PA0 (4) a low noise level of hologram; PA0 (5) a stability of hologram; PA0 (6) easiness of recording and reproducing operations; etc.
On the other hand, with progress in holographic techniques, it is being made possible to form a hologram enduarable to practical use, and uses of holograms have expanded to various fields such that images themselves are enjoyed or holograms are used for decorating a variety of articles, and all sorts of corresponding forms are being required also in holograms.
For example, holograms of the type an uneven pattern corresponding to an image is formed on the surface of the photosensitive material and the image is reproduced by utilizing the light reflected upon or transmitted through the uneven pattern, have been already utilized as covers for books or as marks for preventing forgery or falsification of magnetic cards.
However, in regard to both the above-mentioned properties of the photosensitive materials for use in forming a hologram and the form of a hologram itself, the present state of things is such that there has been provided no hologram that can sufficiently answer the various demands accompanying the uses expanding as mentioned above.
For example, there has not been provided any technique of applying holograms to desired articles with simple operation and with ease, or any form of holograms suited therefor.